Construction chemicals have always been playing important roles in virtually all sorts of construction projects, be it industrial projects, residential building projects, commercial building projects and so on. These chemicals are often used in various elements of projects in order to achieve various important qualities such as workability, durability etc. Construction chemicals exist in many varieties from large number of manufacturers worldwide. Few of the most commonly used varieties have been mentioned below.
Curing compounds : A popular construction chemical widely used in most major projects, especially, industrial ones, these chemicals are often much better substitutes to the conventional method of curing, ie water curing. Curing compounds prevents escape of moisture from freshly laid concrete by sealing the concrete surface and hence water curing becomes unnecessary. They should be compatible to any coating to be applied to the surface. For example, concrete protective coating to be applied in a water or liquid retaining structure may be different from that to be applied to some other structure. Accordingly, the curing compounds should be compatible to the respective types of coatings. For example, MasterSeal 410C is recommended by it’s producer for waterproofing structures while the same producer suggests Masterkure 181S for general purposes.
Curing compounds can be pigmented or clear. They can be membrane forming or non-membrane forming. Curing compounds can be acrylic, linseed oil based, water based, silicate solutions, emulsified paraffin based etc. They can be dissipating, ie non-membrane forming or membrane forming compounds. Example of non-membrane forming curing compound is silicate solution.
Form release agents : These compounds, applied on the inner surfaces of forms, not only facilitate stripping of formwork but also render concrete surfaces smoother. They also help enhancing life-span of the forms. Form releasing agents can be oil based, resin based, water based, organic chemical based etc.
Form sealers : These chemicals are applied along the joints of formwork to render it leakproof and are easier & better options than mortar, jute etc. There are many in the market. One example is polyurethane (PU) sealer quite suitable for plywood forms.
Waterproofing chemicals : These chemicals can be quite useful when a structure’s waterproofing capability is to be given a boost which is especially required for structures constantly dealing with liquids. There are many varieties. Some of them are crystalline waterproofing chemicals, liquid acrylic elastomeric waterproofing compounds, polymer modified waterproofing compounds, cementitious waterproofing compounds etc. Many of these compounds form membranes on the concrete surfaces to protect them from ingress of water.
Water repellents : These chemicals have water repelling properties which is exploited to protect masonry and concrete alike from the ill affects of moisture or water. Some examples amongst many types of water repellent are acrylic protective coating, water based silane siloxane water repellent sealer for tiles, stone masonry etc.
Swelling water stops : These are primarily used in construction joints. Quite easy to install, good quality swelling water stops can be more efficient and economic option to the conventional PVC waterstops in many cases. These chemicals seal the joints by their swelling action when they come in contact with the water of freshly poured concrete. Examples are polyurethane foams and grouts. Swelling PU resins, which turn foamy and expand when coming to contact with water, are used for sealing leaking cracks as well by injecting the chemicals into the cracks.
Contd. in Part II …..